Hirayama Disease

Abstract

A previously healthy 16-year-old female with no family history of neuromuscular disorders presented with a seven year history of hand incoordination. On examination, she had wasting of the intrinsic hand muscles bilaterally, right worse than left. There was no sensory loss, muscle cramping, or pain. Magnetic resonance imaging (MRI) of the cervical spine did not reveal any abnormal findings. Nerve conduction studies identified moderate slowing of the conduction velocity in the right ulnar nerve.One year later, the patient's complaint of hand incoordination continued. Repeat nerve conduction studies revealed conduction blocks in both median nerves in addition to the previously noted decreased conduction velocity in the right ulnar nerve. Followup cervical spine MRI was performed (Figures 1, 2).Magnetic resonance imaging in the neutral position demonstrated subjectively decreased volume and subtly increased T2 hyperintensity in the anterocentral portion of the cervical spinal cord from C5-7 (Figures 1, 2 DISCUSSIONHirayama disease (HD) was first reported in Japan by Dr. K. Hirayama in 1959 and initially labeled "juvenile muscular atrophy of a unilateral (later distal) upper extremity." 1 Hirayama disease is sporadic juvenile muscular atrophy of the distal upper extremities, which predominantly affects young men between 15 and 25 years-of-age. Hirayama disease is characterized by insidious onset of unilateral muscular atrophy and weakness of the hand and forearm, in the absence of sensory or pyramidal signs. Bilateral presentation, though less common, is also known to occur. 2 The clinical course is initially progressive for six to nine years, followed by spontaneous stabilization by the middle of the third decade.1 This disease has had a number of other names some of which include brachial monomelic amyotrophy, benign focal atrophy, benign focal amyotrophy, Sobue's disease, and juvenile segmental muscular atrophy.

Hirayama Disease in Children From North America

“…18 The incidence of cold paresis and tremors on finger extension reported in the literature varies from 27.3% to 97%. 3,7,11,19 Five patients (83%) in our series either gave a history of cold paresis or developed that symptom after they were examined following immersion of their hands in cold water followed by improvement after immersion in warm water. Tremor, when present, also showed similar temperature sensitivity.…”

“…1 The majority of reported cases are from Asia, primarily Japan, 2 and other southern and eastern Asian countries, [3][4][5] with only a few cases from Europe [6][7][8] and North America. [9][10][11][12][13] The symptoms usually start from 1 upper limb and slowly progress to involve the same segments of the contralateral upper limb. 14 Electrodiagnostic examination showing bilateral C8, T1, and C7 segmental denervation with normal sensory nerve conduction is essential in confirming the diagnosis.…”

Cervical Spine MR Imaging Findings of Patients with Hirayama Disease in North America: A Multisite Study

“…[3][4][5][6] To date, there have only been a handful of cases reported from North America, and to our knowledge, there has been no published study characterizing the MR imaging features of this disease in North American patients. [7][8][9][10][11] MR imaging findings reported in patients from Southeast Asia and Japan include LOA of the dura to the lamina, asymmetric lower cervical spinal cord atrophy, spinal cord T2 hyperintensity, loss of cervical lordosis in the neutral position, and forward displacement of the dura with flexion MR imaging. 8 In our experience, HD may be more common in North America than the current literature indicates.…”

Early-onset Hirayama disease in a female

“…As a consequence, neck flexion causes detachment of the tight dura from its posterior anchor and the dura falls forward and causes abutment of the spinal cord against the anterior vertebral column. 1,4,8 Additionally, neck flexion in HD patients results in dysfunction of anterior horn cells, as has been recently demonstrated in a study of 38 HD patients showing an increased number of repeater F-waves during neck flexion. 9 The authors concluded that HD patients should avoid neck flexion for a long period of time.…”

“…However, the early onset in a female, as in our case, has rarely been reported. [2][3][4] Concerning the etiology, it was proposed that a disproportionate growth of the vertebral column and the contents of the spinal canal during the juvenile growth spurt cause HD and the peak of the histogram for onset age is approximately 2 years later than the peak of growth curve. 1 So far, however, this theory remains to be proven.…”